when i use this BS, i get all the characteristics for that Premise, but i want to retrieve only for the char type cd 'ELEVAT', want to know who to restrict in Schema to get data only for 'ELEVAT' char type code, help is appreciated.

You can restrict that both at the UI Map or at the Business Service level. Basically you have to flatten the element. At the UI Map level, you can filter the list with the specific value, similar to XPATH, e.g. ".../resultList/charVal[charTypeCd='XYZ']"

In BPA
tried following three
1. move "CM_PREM/elevation/resultList/charVal" to "CmTestBO/eCharVal";
2. move "CM_PREM/resultList/charVal" to "CmTestBO/eCharVal";
3. move "CM_PREM/resultList[0]/charVal" to "CmTestBO/eCharVal";
none of the above worked.